Wang Fei, Bronich Tatiana K, Kabanov Alexander V, Rauh R David, Roovers Jacques
EIC Laboratories, Incorporated, 111 Downey Street, Norwood, Massachusetts 02062, USA.
Bioconjug Chem. 2008 Jul;19(7):1423-9. doi: 10.1021/bc7004285. Epub 2008 Jun 20.
Two types of 32 arm star polymers incorporating amphiphilic block copolymer arms have been synthesized and characterized. The first type, stPCL-PEG 32, is composed of a polyamidoamine (PAMAM) dendrimer as the core with radiating arms having poly(epsilon-caprolactone) (PCL) as an inner lipophilic block in the arm and poly(ethylene glycol) (PEG) as an outer hydrophilic block. The second type, stPLA-PEG 32, is similar but with poly(L-lactide) (PLA) as the inner lipophilic block. Characterization with SEC, (1)H NMR, FTIR, and DSC confirmed the structure of the polymers. Micelle formation by both star copolymers was studied by fluorescence spectroscopy. The stPCL-PEG 32 polymer exhibited unimolecular micelle behavior. It was capable of solubilizing hydrophobic molecules, such as pyrene, in aqueous solution, while not displaying a critical micelle concentration. In contrast, the association behavior of stPLA-PEG 32 in aqueous solution was characterized by an apparent critical micelle concentration of ca. 0.01 mg/mL. The hydrophobic anticancer drug etoposide can be encapsulated in the micelles formed from both polymers. Overall, the stPCL-PEG 32 polymer exhibited a higher etoposide loading capacity (up to 7.8 w/w % versus 4.3 w/w % for stPLA-PEG 32) as well as facile release kinetics and is more suitable as a potential drug delivery carrier.
已合成并表征了两种含两亲性嵌段共聚物臂的32臂星形聚合物。第一种类型，stPCL-PEG 32，由聚酰胺-胺（PAMAM）树枝状大分子作为核心，其辐射臂具有聚（ε-己内酯）（PCL）作为臂内的亲脂性嵌段和聚（乙二醇）（PEG）作为外部亲水性嵌段。第二种类型，stPLA-PEG 32，与之类似，但以聚（L-丙交酯）（PLA）作为内部亲脂性嵌段。通过尺寸排阻色谱（SEC）、核磁共振氢谱（¹H NMR）、傅里叶变换红外光谱（FTIR）和差示扫描量热法（DSC）对聚合物结构进行了确认。通过荧光光谱研究了两种星形共聚物的胶束形成情况。stPCL-PEG 32聚合物表现出单分子胶束行为。它能够在水溶液中溶解疏水分子，如芘，且未显示出临界胶束浓度。相比之下，stPLA-PEG 32在水溶液中的缔合行为表现为表观临界胶束浓度约为0.01 mg/mL。疏水性抗癌药物依托泊苷可被包裹在由这两种聚合物形成的胶束中。总体而言，stPCL-PEG 32聚合物表现出更高的依托泊苷负载能力（高达7.8 w/w%，而stPLA-PEG 32为4.3 w/w%）以及简便的释放动力学，更适合作为潜在的药物递送载体。
